Drug repurposing in oncology--patient and health systems opportunities

Liver organoids: From fabrication to application in liver diseases

As the largest internal organ, the liver is the key hub for many physiological processes. Previous research on the liver has been mainly conducted on animal models and cell lines, in which not only there are deficiencies in species variability and retention of heritable material, but it is also difficult for primary hepatocytes to maintain their metabolic functions after in vitro expansion. Because of the increased burden of liver disease worldwide, there is a growing demand for 3D in vitro liver models—Liver Organoids. Based on the type of initiation cells, the liver organoid can be classified as PSC-derived or ASC-derived. Liver organoids originated from ASC or primary sclerosing cholangitis, which are co-cultured in matrix gel with components such as stromal cells or immune cells, and eventually form three-dimensional structures in the presence of cytokines. Liver organoids have already made progress in drug screening, individual medicine and disease modeling with hereditary liver diseases, alcoholic or non-alcoholic liver diseases and primary liver cancer. In this review, we summarize the generation process of liver organoids and the current clinical applications, including disease modeling, drug screening and individual medical treatment, which provide new perspectives for liver physiology and disease research.

Molecular Characterization of a First-in-Human Clinical Response to Nimesulide in Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is a hematologic malignancy associated with high morbidity and mortality. Here we describe a case of a patient with AML who presented a partial response after utilization of the non-steroidal anti-inflammatory drug nimesulide. The response was characterized by complete clearance of peripheral blood blasts and an 82% decrease of bone marrow blasts associated with myeloblast differentiation. We have then shown that nimesulide induces in vitro cell death and cell cycle arrest in all AML cell lines (HL-60, THP-1, OCI-AML2, and OCI-AML3). Weighted Correlation Network Analysis (WGCNA) of serial whole-transcriptome data of cell lines treated with nimesulide revealed that the sets of genes upregulated after treatment with nimesulide were enriched for genes associated with autophagy and apoptosis, and on the other hand, the sets of downregulated genes were associated with cell cycle and RNA splicing. Serial transcriptome of bone marrow patient sample confirmed the upregulation of genes associated with autophagy after the response to nimesulide. Lastly, we demonstrated that nimesulide potentiates the cytotoxic in vitro effect of several Food and Drug Administration (FDA)-approved chemotherapy drugs used in AML, including cytarabine.

Multiple deadlocks in the development of nonprofit drugs

The current Coronavirus 2019 (COVID-19) pandemic has shown us that the pharmaceutical research community can organize and administer large nonprofit clinical trials (RECOVERY and SOLIDARITY) and achieve the swift development of common, unpatentable drugs for a new indication: in this case an old, inexpensive drug, dexamethasone, for COVID-19. Why is it that such nonprofit efforts are so rare and are not organized as a systemic, routine part of drug development in the public interest? Based on my own experience with repurposing the alcohol-abuse drug disulfiram (Antabuse) for cancer, I identify at least four serious deadlocks to development of nonprofit drugs. All of these obstacles should be addressed to leverage the potential of the COVID-19 pandemic for better future healthcare systems in all countries around the world.

Drug repositioning in drug discovery of T2DM and repositioning potential of antidiabetic agents

Repositioning or repurposing drugs account for a substantial part of entering approval pipeline drugs, which indicates that drug repositioning has huge market potential and value. Computational technologies such as machine learning methods have accelerated the process of drug repositioning in the last few decades years. The repositioning potential of type 2 diabetes mellitus (T2DM) drugs for various diseases such as cancer, neurodegenerative diseases, and cardiovascular diseases have been widely studied. Hence, the related summary about repurposing antidiabetic drugs is of great significance. In this review, we focus on the machine learning methods for the development of new T2DM drugs and give an overview of the repurposing potential of the existing antidiabetic agents.

The relationships between antihypertensive medications and the overall survival of patients with pancreatic cancer: a systematic review and meta-analysis

BACKGROUND

Antihypertensive medications may have some impacts on cancer. The influence of antihypertensive medications, including angiotensin converting enzyme inhibitors (ACEIs)/angiotensin II receptor blockers (ARBs), beta-blockers, calcium channel blockers (CCBs) and diuretics, on patients with pancreatic cancer (PC) remains controversial. This meta-analysis was conducted to investigate whether antihypertensive medications had a negative effect on the prognosis of patients with PC.

METHODS

The PubMed, Embase, Web of Science and the Cochrane Library databases were searched up to 30 November 2021. The Newcastle-Ottawa scale was used to evaluate the quality of each study. This meta-analysis was registered with PROSPERO (CRD42021279169) and was carried out by using RevMan 5.3.

RESULTS

Twelve studies with 120,549 patients were included in this study. ACEIs/ARBs [HR = 0.89, 95% CI (0.70-1.14)], CCB (HR = 0.69, 95% CI (0.47-0.99)], beta-blockers [HR = 0.95, 95% CI (0.84-1.07)] and diuretics [HR = 1.08, 95% CI (0.91-1.29)] use had no effects on overall survival among patients with PC (all P ≥ 0.05).

CONCLUSION

Antihypertensive medication will not have a negative effect on overall survival in patients with PC. PC patients with hypertension should continue to use antihypertensive medications to reduce the morbidity and mortality of cardiovascular events.

A Potential New Treatment for High-Grade Glioma: A Study Assessing Repurposed Drug Combinations against Patient-Derived High-Grade Glioma Cells

Repurposed drugs have demonstrated in vitro success against high-grade gliomas; however, their clinical success has been limited due to the in vitro model not truly representing the clinical scenario. In this study, we used two distinct patient-derived tumour fragments (tumour core (TC) and tumour margin (TM)) to generate a heterogeneous, clinically relevant in vitro model to assess if a combination of repurposed drugs (irinotecan, pitavastatin, disulfiram, copper gluconate, captopril, celecoxib, itraconazole and ticlopidine), each targeting a different growth promoting pathway, could successfully treat high-grade gliomas. To ensure the clinical relevance of our data, TC and TM samples from 11 different patients were utilized. Our data demonstrate that, at a concentration of 100µm or lower, all drug combinations achieved lower LogIC50 values than temozolomide, with one of the combinations almost eradicating the cancer by achieving cell viabilities below 4% in five of the TM samples 6 days after treatment. Temozolomide was unable to stop tumour growth over the 14-day assay, while combination 1 stopped tumour growth, with combinations 2, 3 and 4 slowing down tumour growth at higher doses. To validate the cytotoxicity data, we used two distinct assays, end point MTT and real-time IncuCyte life analysis, to evaluate the cytotoxicity of the combinations on the TC fragment from patient 3, with the cell viabilities comparable across both assays. The local administration of combinations of repurposed drugs that target different growth promoting pathways of high-grade gliomas have the potential to be translated into the clinic as a novel treatment strategy for high-grade gliomas.

Retinoic Acid Induces an IFN-Driven Inflammatory Tumour Microenvironment, Sensitizing to Immune Checkpoint Therapy

With immune checkpoint therapy (ICT) having reshaped the treatment of many cancers, the next frontier is to identify and develop novel combination therapies to improve efficacy. Previously, we and others identified beneficial immunological effects of the vitamin A derivative tretinoin on anti-tumour immunity. Although it is known that tretinoin preferentially depletes myeloid derived suppressor cells in blood, little is known about the effects of tretinoin on the tumour microenvironment, hampering the rational design of clinical trials using tretinoin in combination with ICT. Here, we aimed to identify how tretinoin changed the tumour microenvironment in mouse tumour models, using flow cytometry and RNAseq, and we sought to use that information to establish optimal dosing and scheduling of tretinoin in combination with several ICT antibodies in multiple cancer models. We found that tretinoin rapidly induced an interferon dominated inflammatory tumour microenvironment, characterised by increased CD8+ T cell infiltration. This phenotype completely overlapped with the phenotype that was induced by ICT itself, and we confirmed that the combination further amplified this inflammatory milieu. The addition of tretinoin significantly improved the efficacy of anti-CTLA4/anti-PD-L1 combination therapy, and staggered scheduling was more efficacious than concomitant scheduling, in a dose-dependent manner. The positive effects of tretinoin could be extended to ICT antibodies targeting OX40, GITR and CTLA4 monotherapy in multiple cancer models. These data show that tretinoin induces an interferon driven, CD8+ T cell tumour microenvironment that is responsive to ICT.

Patient-derived tumor models are attractive tools to repurpose drugs for ovarian cancer treatment: Pre-clinical updates

Despite advances in understanding of ovarian cancer biology, the progress in translation of research findings into new therapies is still slow. It is associated in part with limitations of commonly used cancer models such as cell lines and genetically engineered mouse models that lack proper representation of diversity and complexity of actual human tumors. In addition, the development of de novo anticancer drugs is a lengthy and expensive process. A promising alternative to new drug development is repurposing existing FDA-approved drugs without primary oncological purpose. These approved agents have known pharmacokinetics, pharmacodynamics, and toxicology and could be approved as anticancer drugs quicker and at lower cost. To successfully translate repurposed drugs to clinical application, an intermediate step of pre-clinical animal studies is required. To address challenges associated with reliability of tumor models for pre-clinical studies, there has been an increase in development of patient-derived xenografts (PDXs), which retain key characteristics of the original patient’s tumor, including histologic, biologic, and genetic features. The expansion and utilization of clinically and molecularly annotated PDX models derived from different ovarian cancer subtypes could substantially aid development of new therapies or rapid approval of repurposed drugs to improve treatment options for ovarian cancer patients.

NF-κB Signaling and Inflammation-Drug Repurposing to Treat Inflammatory Disorders?

NF-κB is a central mediator of inflammation, response to DNA damage and oxidative stress. As a result of its central role in so many important cellular processes, NF-κB dysregulation has been implicated in the pathology of important human diseases. NF-κB activation causes inappropriate inflammatory responses in diseases including rheumatoid arthritis (RA) and multiple sclerosis (MS). Thus, modulation of NF-κB signaling is being widely investigated as an approach to treat chronic inflammatory diseases, autoimmunity and cancer. The emergence of COVID-19 in late 2019, the subsequent pandemic and the huge clinical burden of patients with life-threatening SARS-CoV-2 pneumonia led to a massive scramble to repurpose existing medicines to treat lung inflammation in a wide range of healthcare systems. These efforts continue and have proven to be controversial. Drug repurposing strategies are a promising alternative to de novo drug development, as they minimize drug development timelines and reduce the risk of failure due to unexpected side effects. Different experimental approaches have been applied to identify existing medicines which inhibit NF-κB that could be repurposed as anti-inflammatory drugs.

Dissecting the Mechanism of Action of Spiperone-A Candidate for Drug Repurposing for Colorectal Cancer

Simple Summary

Despite advances in primary and adjuvant treatments, approximately 50% of colorectal cancer (CRC) patients still die from recurrence and metastatic disease. Thus, alternative and more effective therapeutic approaches are expected to be developed. Drug repurposing is increasing interest in cancer therapy, as it represents a cheaper and faster alternative strategy to de novo drug synthesis. Psychiatric medications are promising as a new generation of antitumor drugs. Here, we demonstrate that spiperone—a licensed drug for the treatment of schizophrenia—induces apoptosis in CRC cells. Our data reveal that spiperone’s cytotoxicity in CRC cells is mediated by phospholipase C activation, intracellular calcium homeostasis dysregulation, and irreversible endoplasmic reticulum stress induction, resulting in lipid metabolism alteration and Golgi apparatus damage. By identifying new targetable pathways in CRC cells, our findings represent a promising starting point for the design of novel therapeutic strategies for CRC.

Abstract

Approximately 50% of colorectal cancer (CRC) patients still die from recurrence and metastatic disease, highlighting the need for novel therapeutic strategies. Drug repurposing is attracting increasing attention because, compared to traditional de novo drug discovery processes, it may reduce drug development periods and costs. Epidemiological and preclinical evidence support the antitumor activity of antipsychotic drugs. Herein, we dissect the mechanism of action of the typical antipsychotic spiperone in CRC. Spiperone can reduce the clonogenic potential of stem-like CRC cells (CRC-SCs) and induce cell cycle arrest and apoptosis, in both differentiated and CRC-SCs, at clinically relevant concentrations whose toxicity is negligible for non-neoplastic cells. Analysis of intracellular Ca²⁺ kinetics upon spiperone treatment revealed a massive phospholipase C (PLC)-dependent endoplasmic reticulum (ER) Ca²⁺ release, resulting in ER Ca²⁺ homeostasis disruption. RNA sequencing revealed unfolded protein response (UPR) activation, ER stress, and induction of apoptosis, along with IRE1-dependent decay of mRNA (RIDD) activation. Lipidomic analysis showed a significant alteration of lipid profile and, in particular, of sphingolipids. Damage to the Golgi apparatus was also observed. Our data suggest that spiperone can represent an effective drug in the treatment of CRC, and that ER stress induction, along with lipid metabolism alteration, represents effective druggable pathways in CRC.

Drug Combinations: A New Strategy to Extend Drug Repurposing and Epithelial-Mesenchymal Transition in Breast and Colon Cancer Cells

Despite the progressive research and recent advances in drug therapy to treat solid tumours, the number of cases and deaths in patients with cancer is still a major health problem. Drug repurposing coupled to drug combination strategies has been gaining interest among the scientific community. Recently, our group proposed novel drug combinations for breast and colon cancer using repurposed drugs from different classes (antimalarial and central nervous system (CNS)) and chemotherapeutic agents such as 5-fluorouracil (5-FU), paclitaxel (PTX), and found promising results. Here, we proposed a novel drug combination using different CNS drugs and doxorubicin (DOX), an antineoplastic used in breast cancer therapy, and studied their anticancer potential in MCF-7 breast cancer cells. Cells were treated with each drug alone and combined with increasing concentrations of DOX and cell viability was evaluated by MTT and SRB assays. Studies were also complemented with morphological evaluation. Assessment of drug interaction was performed using the CompuSyn and SynergyFinder software. We also compiled our previously studied drug pairs and selected the most promising ones for evaluation of the expression of EMT biomarkers (E-cadherin, P-cadherin, vimentin, and β-catenin) by immunohistochemistry (IHC) to assess if these drug combinations affect the expression of these proteins and eventually revert EMT. These results demonstrate that combination of DOX plus fluoxetine, benztropine, and thioridazine at their IC50 can improve the anticancer effect of DOX but to a lesser degree than when combined with PTX (previous results), resulting in most of the drug interactions being antagonist or additive. This suggests that the choice of the antineoplastic drug influences the success of the drug combination. Collectively, these results also allow us to conclude that antimalarial drugs as repurposed drugs have enhanced effects in MCF-7 breast cancer cells, while combination with CNS drugs seems to be more effective in HT-29 colon cancer cells. The IHC results demonstrate that combination treatments increase E-cadherin expression while reducing P-cadherin, vimentin, and β-catenin, suggesting that these treatments could induce EMT reversal. Taken together, these results could provide promising approaches to the design of novel drug combinations to treat breast and colon cancer patients.

Tackling the Behavior of Cancer Cells: Molecular Bases for Repurposing Antipsychotic Drugs in the Treatment of Glioblastoma

Glioblastoma (GBM) is associated with a very dismal prognosis, and current therapeutic options still retain an overall unsatisfactorily efficacy in clinical practice. Therefore, novel therapeutic approaches and effective medications are highly needed. Since the development of new drugs is an extremely long, complex and expensive process, researchers and clinicians are increasingly considering drug repositioning/repurposing as a valid alternative to the standard research process. Drug repurposing is also under active investigation in GBM therapy, since a wide range of noncancer and cancer therapeutics have been proposed or investigated in clinical trials. Among these, a remarkable role is played by the antipsychotic drugs, thanks to some still partially unexplored, interesting features of these agents. Indeed, antipsychotic drugs have been described to interfere at variable incisiveness with most hallmarks of cancer. In this review, we analyze the effects of antipsychotics in oncology and how these drugs can interfere with the hallmarks of cancer in GBM. Overall, according to available evidence, mostly at the preclinical level, it is possible to speculate that repurposing of antipsychotics in GBM therapy might contribute to providing potentially effective and inexpensive therapies for patients with this disease.

Two Possible Strategies for Drug Modification of Gemcitabine and Future Contributions to Personalized Medicine

Drug repurposing is an emerging strategy, which uses already approved drugs for new medical indications. One such drug is gemcitabine, an anticancer drug that only works at high doses since a portion is deactivated in the serum, which causes toxicity. In this review, two methods were discussed that could improve the anticancer effect of gemcitabine. The first is a chemical modification by conjugation with cell-penetrating peptides, namely penetratin, pVEC, and different kinds of CPP6, which mostly all showed an increased anticancer effect. The other method is combining gemcitabine with repurposed drugs, namely itraconazole, which also showed great cancer cell inhibition growth. Besides these two strategies, physiologically based pharmacokinetic models (PBPK models) are also the key for predicting drug distribution based on physiological data, which is very important for personalized medicine, so that the correct drug and dosage regimen can be administered according to each patient’s physiology. Taking all of this into consideration, it is believed that gemcitabine can be repurposed to have better anticancer effects.

Once-monthly hemin suppresses inflammatory and autoreactive CD4+ T cell responses to robustly ameliorate experimental rheumatoid arthritis

Rheumatoid arthritis (RA) is an inflammatory autoimmune disease that would permanently damage the affected joints. Unfortunately, a large proportion of RA patients fail to respond adequately to current treatments. Here, repurposing hemin and its ultra-long-acting formulation were explored for the effective treatment of RA in animal models. We provided evidence that hemin prevented the onset and ameliorated the clinical course of RA. Notably, hemin treatment rescued the dysregulated gene expression in animal models of RA, resulting in attenuation of Th1/Th17 cell-mediated responses and proinflammatory cytokines. Moreover, we further formulated hemin into the in-situ forming implant, and a single injection of the ultra-long-acting hemin exerted potent disease-modifying effects for at least six weeks with a remarkable dose reduction. Taken together, given the potent anti-inflammatory and immunosuppressive effects, the once-monthly hemin injection holds promise for rapid clinical translation, and represents a potential strategy to treat RA and possibly other autoimmune diseases.

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Repurposing hemin prevents the onset and ameliorates the clinical course of RA

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Once-monthly hemin achieve sustained remission of RA for at least six weeks

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Hemin rescue dysregulated gene expression and attenuate autoreactive immune responses

Repurposing drugs as novel triple negative breast cancer therapeutics

BACKGROUND

Among all the types of breast cancer (BC), triple negative breast cancer (TNBC) is the most aggressive form having high metastasis and recurrence rate with limited treatment options. Conventional treatments such as chemotherapy and radiotherapy have lots of toxic side effects and also no FDA approved therapies are available till now. Repurposing of old clinically approved drugs towards various targets of TNBC is the new approach with lesser side effects and also leads to successful inexpensive drug development with less time consuming. Medicinal plants containg various phytoconstituents (flavonoids, alkaloids, phenols, essential oils, tanins, glycosides, lactones) plays very crucial role in combating various types of diseases and used in drug development process because of having lesser side effects.

OBJECTIVE

The present review focuses in summarization of various categories of repurposed drugs against multitarget of TNBC and also summarizes the phytochemical categories that targets TNBC singly or in combination with synthetic old drugs.

METHODS

Literature information was collected from various databases such as Pubmed, Web of Science, Scopus and Medline to understand and clarify the role and mechanism of repurposed synthetic drugs and phytoconstituents aginst TNBC by using keywords like "breast cancer", "repurposed drugs", "TNBC" and "phytoconstituents".

RESULTS

Various repurposed drugs and phytochemicals targeting different signaling pathways that exerts their cytotoxic activities on TNBC cells ultimately leads to apoptosis of cells and also lowers the recurrence rate and stops the metastasis process.

CONCLUSION

Inhibitory effects seen in different levels, which provides information and evidences to researchers towards drug developments process and thus further more investigations and researches need to be taken to get the better therapeutic treatment options against TNBC.

Recent Advances in Repurposing Disulfiram and Disulfiram Derivatives as Copper-Dependent Anticancer Agents

Copper (Cu) plays a pivotal role in cancer progression by acting as a co-factor that regulates the activity of many enzymes and structural proteins in cancer cells. Therefore, Cu-based complexes have been investigated as novel anticancer metallodrugs and are considered as a complementary strategy for currently used platinum agents with undesirable general toxicity. Due to the high failure rate and increased cost of new drugs, there is a global drive towards the repositioning of known drugs for cancer treatment in recent years. Disulfiram (DSF) is a first-line antialcoholism drug used in clinics for more than 65 yr. In combination with Cu, it has shown great potential as an anticancer drug by targeting a wide range of cancers. The reaction between DSF and Cu ions forms a copper diethyldithiocarbamate complex (Cu(DDC)₂ also known as CuET) which is the active, potent anticancer ingredient through inhibition of NF-κB and ubiquitin-proteasome system as well as alteration of the intracellular reactive oxygen species (ROS). Importantly, DSF/Cu inhibits several molecular targets related to drug resistance, stemness, angiogenesis and metastasis and is thus considered as a novel strategy for overcoming tumour recurrence and relapse in patients. Despite its excellent anticancer efficacy, DSF has proven unsuccessful in several cancer clinical trials. This is likely due to the poor stability, rapid metabolism and/or short plasma half-life of the currently used oral version of DSF and the inability to form Cu(DDC)₂ at relevant concentrations in tumour tissues. Here, we summarize the scientific rationale, molecular targets, and mechanisms of action of DSF/Cu in cancer cells and the outcomes of oral DSF ± Cu in cancer clinical trials. We will focus on the novel insights on harnessing the immune system and hypoxic microenvironment using DSF/Cu complex and discuss the emerging delivery strategies that can overcome the shortcomings of DSF-based anticancer therapies and provide opportunities for translation of DSF/Cu or its Cu(DDC)₂ complex into cancer therapeutics.

Combining repurposed drugs to treat colorectal cancer

The drug development process, especially of antineoplastic agents, has become increasingly costly and ineffective. Drug repurposing and drug combination are alternatives to de novo drug development, being low cost, rapid, and easy to apply. These strategies allow higher efficacy, decreased toxicity, and overcoming of drug resistance. The combination of antineoplastic agents is already being applied in cancer therapy, but the combination of repurposed drugs is still under-explored in pre- and clinical development. In this review, we provide a set of pharmacological concepts focusing on drug repurposing for treating colorectal cancer (CRC) and that are relevant for the application of new drug combinations against this disease.

Use of non-cancer drugs and survival among patients with pancreatic adenocarcinoma: a nationwide registry-based study in Norway

BACKGROUND

The prognosis of pancreatic cancer is poor and new treatment strategies are urgently needed. To identify non-cancer drugs that could be re-purposed for cancer, we investigated the association between the use of selected drugs and cancer-specific mortality in a nationwide cohort of pancreatic cancer patients.

MATERIAL AND METHODS

The study is based on linkage between the Cancer Registry of Norway and the Norwegian Prescription Database, comprising 2614 pancreatic cancer patients diagnosed between 2007 and 2014. We evaluated the association between use at diagnosis of a pre-defined list of non-cancer drugs, including metformin, antihypertensives, and statins, and pancreatic cancer-specific mortality, using Cox regression. Patients were defined as users of a particular drug if it was prescribed before diagnosis, and the prescription covered the date of diagnosis.

RESULTS

In total, 2096 (80.2%) patients died from pancreatic cancer; median survival was 6 months. Statin users (n = 621) had lower mortality (hazard ratio (HR): 0.86; 95% confidence interval (CI) 0.76-0.97) compared to non-users (n = 1993). This association was more pronounced (P-heterogeneity 0.062) in users of hydrophilic (n = 37, HR: 0.61; 95% CI 0.42-0.90) than lipophilic (n = 587, HR: 0.87; 95% CI 0.78-0.98) statins. An indication for lower mortality (HR: 0.85; 95% CI 0.69-1.05) was observed in users of non-selective beta-blockers (n = 113) compared to non-users (n = 2501). Notably, when compared to users of other antihypertensives (n = 643), users of non-selective beta-blockers (n = 40) had lower mortality (HR 0.67; 95% CI 0.47-0.96). The use of other drugs, including selective beta-blockers and metformin, was not associated with mortality.

CONCLUSION

The findings suggest an association between the use of statins and non-selective beta-blockers and reduced pancreatic cancer mortality, and add to the literature supporting the design of randomised clinical trials to evaluate those drugs in the management of pancreatic cancer.

High Drug Resistance in Feline Mammary Carcinoma Cell Line (FMCm) and Comparison with Human Breast Cancer Cell Line (MCF-7)

Drug repurposing and drug combination are important therapeutic approaches in cancer therapy. Drug repurposing aims to give new indications to drugs, rather than the original indication, whereas drug combination presupposes that the effect that is obtained should be more beneficial than the effect obtained by the individual drugs. Previously, drug repurposing and the combination of different drugs was evaluated in our research group against human breast cancer cells (MCF-7 cells). Our results demonstrated that the response obtained through the combination of drugs, when compared with the single drugs, led to more synergic responses. Therefore, using potential drugs for repurposing, combined with a reference drug in breast cancer (5-Fluorouracil), was the major aim of this project, but for the first time using the feline mammary carcinoma cell line, FMCm. Surprisingly, the feline neoplastic cells demonstrated considerable resistance to the drugs tested in isolation, and the combination was not effective, which contrasted with the obtained MCF-7 cells' response.

A Synergistic Combination of Niclosamide and Doxorubicin as an Efficacious Therapy for All Clinical Subtypes of Breast Cancer

Simple Summary

Chemotherapy is the gold standard treatment option for metastatic cancers. However, the efficacy of chemotherapy is limited due to the development of resistance. The aberrantly expressed Wnt/β-catenin signaling pathway acts as one of the major cancer drivers that also causes the development of resistance. Therefore, in this study, we explored the combinatorial approach of downregulating the Wnt/β-catenin pathway along with using a chemotherapeutic agent as a strategy to overcome drug resistance and improve cancer therapy. We evaluated the combinatorial efficacy of Niclosamide (an antihelminthic repurposed as a Wnt signaling inhibitor) and Doxorubicin (first-line treatment for multiple cancers in the clinic) against breast cancer. The combination showed synergistically enhanced death of all three clinical subtypes of breast cancer cells in both the sequential and concurrent treatment regimens and holds the potential to be developed as an efficient therapeutic option for breast cancer irrespective of its clinical subtype.

Abstract

Drug resistance is one of the major hurdles in the success of cancer chemotherapy. Notably, aberrantly expressed Wnt/β-catenin signaling plays a major role in the initiation and maintenance of oncogenesis along with development of chemoresistance. Therefore, the combinatorial approach of targeting Wnt/β-catenin pathway along with using a chemotherapeutic agent seems to be a promising strategy to improve cancer therapy. In the present study, we evaluated the combination of niclosamide (Nic), an FDA-approved antihelminthic drug repurposed as a Wnt signaling inhibitor, and doxorubicin (Dox), a conventional anticancer agent, in all clinical subtypes of breast cancer viz. triple negative breast cancer, HER2 positive breast cancer, and hormone receptor positive breast cancer. The results demonstrated that the combination induced apoptosis and caused synergistically enhanced death of all breast cancer cell types at multiple combinatorial concentrations using both the sequential and concurrent treatment regimens. Mechanistically, downregulation of Wnt/β-catenin signaling and cell cycle arrest at G0/G1 phase by Nic and increase in reactive oxygen species by both Nic and Dox along with the inherent cytotoxicity of Dox mediated the synergism between the two drugs in both the treatment regimens. Overall, the combination of Nic and Dox holds promise to be developed as an efficient therapeutic option for breast cancer irrespective of its clinical subtype.

Repurposing existing therapeutics, its importance in oncology drug development: Kinases as a potential target

Repurposing the large arsenal of existing non‐cancer drugs is an attractive proposition to expand the clinical pipelines for cancer therapeutics. The earlier successes in repurposing resulted primarily from serendipitous findings, but more recently, drug or target‐centric systematic identification of repurposing opportunities continues to rise. Kinases are one of the most sought‐after anti‐cancer drug targets over the last three decades. There are many non‐cancer approved drugs that can inhibit kinases as “off‐targets” as well as many existing kinase inhibitors that can target new additional kinases in cancer. Identifying cancer‐associated kinase inhibitors through mining commercial drug databases or new kinase targets for existing inhibitors through comprehensive kinome profiling can offer more effective trial‐ready options to rapidly advance drugs for clinical validation. In this review, we argue that drug repurposing is an important approach in modern drug development for cancer therapeutics. We have summarized the advantages of repurposing, the rationale behind this approach together with key barriers and opportunities in cancer drug development. We have also included examples of non‐cancer drugs that inhibit kinases or are associated with kinase signalling as a basis for their anti‐cancer action.

Repurposing of Antimicrobial Agents for Cancer Therapy: What Do We Know?

The substantial costs of clinical trials, the lengthy timelines of new drug discovery and development, along the high attrition rates underscore the need for alternative strategies for finding quickly suitable therapeutics agents. Given that most approved drugs possess more than one target tightly linked to other diseases, it encourages promptly testing these drugs in patients. Over the past decades, this has led to considerable attention for drug repurposing, which relies on identifying new uses for approved or investigational drugs outside the scope of the original medical indication. The known safety of approved drugs minimizes the possibility of failure for adverse toxicology, making them attractive de-risked compounds for new applications with potentially lower overall development costs and shorter development timelines. This latter case is an exciting opportunity, specifically in oncology, due to increased resistance towards the current therapies. Indeed, a large body of evidence shows that a wealth of non-cancer drugs has beneficial effects against cancer. Interestingly, 335 drugs are currently being evaluated in different clinical trials for their potential activities against various cancers (Redo database). This review aims to provide an extensive discussion about the anti-cancer activities exerted by antimicrobial agents and presents information about their mechanism(s) of action and stage of development/evaluation.

Anticancer activity of repurposed hemostatic agent desmopressin on AVPR2-expressing human osteosarcoma

Osteosarcoma is the most prevalent primary bone malignancy. Due to its high aggressiveness, novel treatment strategies are urgently required to improve survival of patients with osteosarcoma, especially those with advanced disease. Desmopressin (dDAVP) is a widely used blood-saving agent that has been repurposed as an adjuvant agent for cancer management due to its antiangiogenic and antimetastatic properties. dDAVP acts as a selective agonist of the vasopressin membrane receptor type 2 (AVPR2) present in the microvascular endothelium and in some cancer cells, including breast, lung, colorectal and neuroendocrine tumor cells. Despite the fact that dDAVP has demonstrated its antitumor efficacy in a wide variety of tumor types, exploration of its potential anti-osteosarcoma activity has, to the best of our knowledge, not yet been conducted. Therefore, the aim of the present study was to evaluate the preclinical antitumor activity of dDAVP in osteosarcoma. Human MG-63 and U-2 OS osteosarcoma cell lines were used to assess in vitro and in vivo therapeutic effects of dDAVP. At low micromolar concentrations, dDAVP reduced AVPR2-expressing MG-63 cell growth in a concentration-dependent manner. In contrast, dDAVP exhibited no direct cytostatic effect on AVPR2-negative U-2 OS cells. As it would be expected for canonical AVPR2-activation, dDAVP raised intracellular cAMP levels in osteosarcoma cells, and coincubation with phosphodiesterase-inhibitor rolipram indicated synergistic antiproliferative activity. Cytostatic effects were associated with increased apoptosis, reduced mitotic index and impairment of osteosarcoma cell chemotaxis, as evaluated by TUNEL-labeling, mitotic body count in DAPI-stained cultures and Transwell migration assays. Intravenous administration of dDAVP (12 µg/kg; three times per week) to athymic mice bearing rapidly growing MG-63 xenografts, was indicated to be capable of reducing tumor progression after a 4-week treatment. No major alterations in animal weight, biochemical or hematological parameters were associated with dDAVP treatment, confirming its good tolerability and safety. Finally, AVPR2 expression was detected by immunohistochemistry in 66% of all evaluated chemotherapy-naive human conventional osteosarcoma biopsies. Taking these findings into account, repurposed agent dDAVP may represent an interesting therapeutic tool for the management of osteosarcoma. Further preclinical exploration of dDAVP activity on orthotopic or metastatic osteosarcoma models are required.

Drug Repurposing in Oncology: Current Evidence and Future Direction

BACKGROUND

Drug repurposing, the application of known drugs and compounds with a primary non-oncology purpose, might be an attractive strategy to offer more effective treatment options to cancer patients at a low cost and reduced time.

METHODS

This review described a total of 10 kinds of non-oncological drugs from more than 100 mechanical studies as well as evidence from population-based studies. The future direction of repurposed drug screening is discussed by using patient-derived tumor organoids.

RESULTS

Many old drugs showed previously unknown effects or off-target effects and can be intelligently applied for cancer chemoprevention and therapy. The identification of repurposed drugs needs to combine evidence from mechanical studies and population-based studies. Due to the heterogeneity of cancer, patient-derived tumor organoids can be used to screen the non-oncological drugs in vitro.

CONCLUSION

These identified old drugs could be repurposed in oncology and might be added as adjuvants and finally benefit patients with cancers.

Drug Repurposing in Oncology, an Attractive Opportunity for Novel Combinatorial Regimens

The costs of developing, validating and buying new drugs are dramatically increasing. On the other hand, sobering economies have difficulties in sustaining their healthcare systems, particularly in countries with an elderly population requiring increasing welfare. This conundrum requires immediate action, and a possible option is to study the large, already present arsenal of drugs approved and to use them for innovative therapies. This possibility is particularly interesting in oncology, where the complexity of the cancer genome dictates in most patients a multistep therapeutic approach. In this review, we discuss a) Computational approaches; b) preclinical models; c) currently ongoing or already published clinical trials in the drug repurposing field in oncology; and d) drug repurposing to overcome resistance to previous therapies.

An integrated virtual screening and drug repurposing strategy for the discovery of new antimalarial drugs against Plasmodium falciparum phosphatidylinositol 3-kinase

The emergence and spread of drug resistance in Plasmodium falciparum, the parasite causing the most severe form of human malaria, is a major threat to malaria control and elimination programs around the globe. With P. falciparum having evolved widespread resistance against a number of previously widely used drugs, currently, artemisinin (ART) and its derivatives are the cornerstones of first-line treatments of uncomplicated malaria. However, growing incidences of ART failure reflect the spread of ART-resistant P. falciparum strains. Despite current efforts to understand the primary cause of ART resistance due to mutations in the Kelch 13 gene (PfK13), the mechanism underlying ART resistance is still not completely unclear and no feasible strategies to counteract the causes and thereby restoring the efficiency of ART have been developed. We use a polypharmacology approach to identify potential drugs that can be used for the novel purpose (target). Of note, we have designed a multimodal stratagem to identify approved drugs with a potential antimalarial activity using computational drug reprofiling. Our investigations suggest that oxetacaine, simvastatin, repaglinide, aclidinium, propafenone, and lovastatin could be repurposed for malaria control and prevention.

El-kherbetawy M, El-mistekawy A, Mohammad HMF, Elbahaie AM, Hashish AA, Alomar SY, Aloyouni SY, El-dosoky M, Morsy KM, Zaitone SA. Antitumor Activity of Nitazoxanide against Colon Cancers: Molecular Docking and Experimental Studies Based on Wnt/β-Catenin Signaling Inhibition

In colon cancer, wingless (Wnt)/β-catenin signaling is frequently upregulated; however, the creation of a molecular therapeutic agent targeting this pathway is still under investigation. This research aimed to study how nitazoxanide can affect Wnt/β-catenin signaling in colon cancer cells (HCT-116) and a mouse colon cancer model. Our study included 2 experiments; the first was to test the cytotoxic activity of nitazoxanide in an in vitro study on a colon cancer cell line (HCT-116) versus normal colon cells (FHC) and to highlight the proapoptotic effect by MTT assay, flow cytometry and real-time polymerase chain reaction (RT-PCR). The second experiment tested the in vivo cytotoxic effect of nitazoxanide against 1,2-dimethylhydrazine (DMH) prompted cancer in mice. Mice were grouped as saline, DMH control and DMH + nitazoxanide [100 or 200 mg per kg]. Colon levels of Wnt and β-catenin proteins were assessed by Western blotting while proliferation was measured via immunostaining for proliferating cell nuclear antigen (PCNA). Treating HCT-116 cells with nitazoxanide (inhibitory concentration 50 (IC50) = 11.07 µM) revealed that it has a more cytotoxic effect when compared to 5-flurouracil (IC50 = 11.36 µM). Moreover, it showed relatively high IC50 value (non-cytotoxic) against the normal colon cells. Nitazoxanide induced apoptosis by 15.86-fold compared to control and arrested the cell cycle. Furthermore, nitazoxanide upregulated proapoptotic proteins (P53 and BAX) and caspases but downregulated BCL-2. Nitazoxanide downregulated Wnt/β-catenin/glycogen synthase kinase-3β (GSK-3β) signaling and PCNA staining in the current mouse model. Hence, our findings highlighted the cytotoxic effect of nitazoxanide and pointed out the effect on Wnt/β-catenin/GSK-3β signaling.

Repurposing Infectious Diseases Vaccines Against Cancer

Vaccines used to prevent infections have long been known to stimulate immune responses to cancer as illustrated by the approval of the Bacillus Calmette-Guérin (BCG) vaccine to treat bladder cancer since the 1970s. The recent approval of immunotherapies has rejuvenated this research area with reports of anti-tumor responses with existing infectious diseases vaccines used as such, either alone or in combination with immune checkpoint inhibitors. Here, we have reviewed and summarized research activities using approved vaccines to treat cancer. Data supporting a cancer therapeutic use was found for 16 vaccines. For 10 (BCG, diphtheria, tetanus, human papillomavirus, influenza, measles, pneumococcus, smallpox, typhoid and varicella-zoster), clinical trials have been conducted or are ongoing. Within the remaining 6, preclinical evidence supports further evaluation of the rotavirus, yellow fever and pertussis vaccine in carefully designed clinical trials. The mechanistic evidence for the cholera vaccine, combined with the observational data in colorectal cancer, is also supportive of clinical translation. There is limited data for the hepatitis B and mumps vaccine (without measles vaccine). Four findings are worth highlighting: the superiority of intravesical typhoid vaccine instillations over BCG in a preclinical bladder cancer model, which is now the subject of a phase I trial; the perioperative use of the influenza vaccine to limit and prevent the natural killer cell dysfunction induced by cancer surgery; objective responses following intratumoral injections of measles vaccine in cutaneous T-cell lymphoma; objective responses induced by human papillomavirus vaccine in cutaneous squamous cell carcinoma. All vaccines are intended to induce or improve an anti-tumor (immune) response. In addition to the biological and immunological mechanisms that vary between vaccines, the mode of administration and sequence with other (immuno-)therapies warrant more attention in future research.

Calcium channel blockers in pancreatic cancer: increased overall survival in a retrospective cohort study

Repurposing commonly prescribed noncancer medications for use in oncology has substantial advantages over de-novo development of anticancer drugs. Calcium signalling has been implicated in many of the hallmarks of cancer. Previous in-vitro and in-vivo studies have shown that calcium channel blockers (CCBs) are able to promote apoptosis, inhibit proliferation and prevent invasion and metastasis in a variety of cancer types. This retrospective cohort study aimed to translate this into the clinic by investigating the effect of CCBs on survival in pancreatic cancer. One hundred sixty-four patients with unresectable pancreatic ductal adenocarcinoma were included. Data were collected on CCB prescription, and for a range of other potentially important prognostic factors: ECOG performance status, AJCC cancer stage, chemotherapy regimen, radiotherapy, age, hypertension and sex. Participants prescribed CCB (n = 30) were more likely to be older (P = 0.004) and have hypertension (P < 0.0005); baseline demographics were otherwise similar between groups. On adjusted cox regression patients prescribed CCBs demonstrated significantly improved overall survival; hazard ratio -0.496 (0.297-0.827; P = 0.007). Performance status (P < 0.0005), tumour stage (P < 0.0005), chemotherapy regimen (P < 0.0005), radiotherapy (0.002) and age (P = 0.012) were also independent predictors of survival. The Kaplan-Meier estimated median survival was 15.3 months for patients prescribed CCBs versus 10.1 months for patients not prescribed CCBs (P = 0.131). This study supports previous work suggesting CCBs may be beneficial in pancreatic cancer. Further work on larger datasets will allow for subgroup analysis delineating the effects of specific CCBs in combination with different forms of chemotherapy, paving the way for future prospective studies.

Exploring new uses for existing drugs: innovative mechanisms to fund independent clinical research

BACKGROUND

Finding new therapeutic uses for existing medicines could lead to safe, affordable and timely new treatment options for patients with high medical needs. However, due to a lack of economic incentives, pharmaceutical developers are rarely interested to invest in research with approved medicines, especially when they are out of basic patent or regulatory protection. Consequently, potential new uses for these medicines are mainly studied in independent clinical trials initiated and led by researchers from academia, research institutes, or collaborative groups. Yet, additional financial support is needed to conduct expensive phase III clinical trials to confirm the results from exploratory research.

METHODS

In this study, scientific and grey literature was searched to identify and evaluate new mechanisms for funding clinical trials with repurposed medicines. Semi-structured interviews were conducted with 16 European stakeholders with expertise in clinical research, funding mechanisms and/or drug repurposing between November 2018 and February 2019 to consider the future perspectives of applying new funding mechanisms.

RESULTS

Traditional grant funding awarded by government and philanthropic organisations or companies is well known and widely implemented in all research fields. In contrast, only little research has focused on the application potential of newer mechanisms to fund independent clinical research, such as social impact bonds, crowdfunding or public-private partnerships. Interviewees stated that there is a substantial need for additional financial support in health research, especially in areas where there is limited commercial interest. However, the implementation of new funding mechanisms is facing several practical and financial challenges, such as a lack of expertise and guidelines, high transaction costs and difficulties to measure health outcomes. Furthermore, interviewees highlighted the need for increased collaboration and centralisation at a European and international level to make clinical research more efficient and reduce the need for additional funding.

CONCLUSIONS

New funding mechanisms to support clinical research may become more important in the future but the unresolved issues identified in the current study warrant further exploration.

Screening of Benzimidazole-Based Anthelmintics and Their Enantiomers as Repurposed Drug Candidates in Cancer Therapy

Repurposing of approved non-antitumor drugs represents a promising and affordable strategy that may help to increase the repertoire of effective anticancer drugs. Benzimidazole-based anthelmintics are antiparasitic drugs commonly employed both in human and veterinary medicine. Benzimidazole compounds are being considered for drug repurposing due to antitumor activities displayed by some members of the family. In this study, we explored the effects of a large series of benzimidazole-based anthelmintics (and some enantiomerically pure forms of those containing a stereogenic center) on the viability of different tumor cell lines derived from paraganglioma, pancreatic and colorectal cancer. Flubendazole, parbendazole, oxibendazole, mebendazole, albendazole and fenbendazole showed the most consistent antiproliferative effects, displaying IC₅₀ values in the low micromolar range, or even in the nanomolar range. In silico evaluation of their physicochemical, pharmacokinetics and medicinal chemistry properties also provided useful information related to the chemical structures and potential of these compounds. Furthermore, in view of the potential repurposing of these drugs in cancer therapy and considering that pharmaceutically active compounds may have different mechanisms of action, we performed an in silico target prediction to assess the polypharmacology of these benzimidazoles, which highlighted previously unknown cancer-relevant molecular targets.

Drug Use and Cancer Risk: A Drug-Wide Association Study (DWAS) in Norway

BACKGROUND

Population-based pharmaco-epidemiologic studies are used to assess postmarketing drug safety and discover beneficial effects of off-label drug use. We conducted a drug-wide association study (DWAS) to screen for associations between prescription drugs and cancer risk.

METHODS

This registry-based, nested case-control study, 1:10 matched on age, sex, and date of diagnosis of cases, comprises approximately 2 million Norwegian residents, including their drug history from 2004 to 2014. We evaluated the association between prescribed drugs, categorized according to the anatomical therapeutic chemical (ATC) classification system, and the risk of the 15 most common cancer types, overall and by histology. We used stratified Cox regression, adjusted for other drug use, comorbidity, county, and parity, and explored dose-response trends.

RESULTS

We found 145 associations among 1,230 drug-cancer combinations on the ATC2-level and 77 of 8,130 on the ATC4-level. Results for all drug-cancer combinations are presented in this article and an online tool (https://pharmacoepi.shinyapps.io/drugwas/). Some associations have been previously reported, that is, menopausal hormones and breast cancer risk, or are likely confounded, that is, chronic obstructive pulmonary diseases and lung cancer risk. Other associations were novel, that is, inverse association between proton pump inhibitors and melanoma risk, and carcinogenic association of propulsives and lung cancer risk.

CONCLUSIONS

This study confirmed previously reported associations and generated new hypotheses on possible carcinogenic or chemopreventive effects of prescription drugs. Results from this type of explorative approach need to be validated in tailored epidemiologic and preclinical studies.

IMPACT

DWAS studies are robust and important tools to define new drug-cancer hypotheses.See related commentary by Wang and Gadalla, p. 597.

Preclinical efficacy of ribavirin in SHH and group 3 medulloblastoma

OBJECTIVE

Medulloblastoma, the most common pediatric brain malignancy, has Sonic Hedgehog (SHH) and group 3 (Myc driven) subtypes that are associated with the activity of eukaryotic initiation factor 4E (eIF4E), a critical mediator of translation, and enhancer of zeste homolog 2 (EZH2), a histone methyltransferase and master regulator of transcription. Recent drug repurposing efforts in multiple solid and hematologic malignancies have demonstrated that eIF4E and EZH2 are both pharmacologically inhibited by the FDA-approved antiviral drug ribavirin. Given the molecular overlap between medulloblastoma biology and known ribavirin activity, the authors investigated the preclinical efficacy of repurposing ribavirin as a targeted therapeutic in cell and animal models of medulloblastoma.

METHODS

Multiple in vitro assays were performed using human ONS-76 (a primitive SHH model) and D425 (an aggressive group 3 model) cells. The impacts of ribavirin on cellular growth, death, migration, and invasion were quantified using proliferation and Cell Counting Kit-8 (CCK-8) assays, flow cytometry with annexin V (AnnV) staining, scratch wound assays, and Matrigel invasion chambers, respectively. Survival following daily ribavirin treatment (100 mg/kg) was assessed in vivo in immunodeficient mice intracranially implanted with D425 cells.

RESULTS

Compared to controls, ribavirin treatment led to a significant reduction in medulloblastoma cell growth (ONS-76 proliferation assay, p = 0.0001; D425 CCK-8 assay, p < 0.0001) and a significant increase in cell death (flow cytometry for AnnV, ONS-76, p = 0.0010; D425, p = 0.0284). In ONS-76 cells, compared to controls, ribavirin significantly decreased cell migration and invasion (Matrigel invasion chamber assay, p = 0.0012). In vivo, ribavirin significantly extended survival in an aggressive group 3 medulloblastoma mouse model compared to vehicle-treated controls (p = 0.0004).

CONCLUSIONS

The authors demonstrate that ribavirin, a clinically used drug known to inhibit eIF4E and EZH2, has significant antitumor effects in multiple preclinical models of medulloblastoma, including an aggressive group 3 animal model. Ribavirin may represent a promising targeted therapeutic in medulloblastoma.

Combination of Fish Oil and Selenium Enhances Anticancer Efficacy and Targets Multiple Signaling Pathways in Anti-VEGF Agent Treated-TNBC Tumor-Bearing Mice

Fish oil (FO) and selenium (Se) possess antiangiogenic potential in malignant tumors. This study aimed to determine whether combination of FO and Se enhanced treatment efficacy of low-dose antiangiogenic agent Avastin (bevacizumab) in a dose-dependent manner and targeted multiple signaling pathways in triple-negative breast cancer (TNBC)-bearing mice. Randomized into five groups, mice received treatment with either physiological saline (control), Avastin alone, or Avastin in combination with low, medium, and high doses of FO/Se. The target signaling molecules for anticancer were determined either by measuring protein or mRNA expression. Avastin-treated mice receiving FO/Se showed lower tumor growth and metastasis than did mice treated with Avastin alone. Combination-treated mice exhibited lower expressions in multiple proangiogenic (growth) factors and their membrane receptors, and altered cytoplasmic signaling molecules (PI3K-PTEN-AKT-TSC-mTOR-p70S6K-4EBP1, Ras-Raf-MEK-ERK, c-Src-JAK2-STAT3-TMEPAI-Smad, LKB1-AMPK, and GSK3β/β-catenin). Dose-dependent inhibition of down-stream targets including epithelial-to-mesenchymal transition transcription factors, nuclear cyclin and cyclin-dependent kinases, cancer stem cell markers, heat shock protein (HSP-90), hypoxia-inducible factors (HIF-1α/-2α), matrix metalloprotease (MMP-9), and increased apoptosis were observed. These results suggest that combination treatment with FO and Se increases the therapeutic efficacy of Avastin against TNBC in a dose-dependent manner through multiple signaling pathways in membrane, cytoplasmic, and nucleic targets.

Ribavirin inhibits colorectal cancer growth by downregulating PRMT5 expression and H3R8me2s and H4R3me2s accumulation

Eukaryotic translation initiation factor 4E (eIF4E) and protein arginine methyltransferase 5 (PRMT5) are frequently overexpressed in colorectal cancer (CRC) tissues and associated with poor prognosis. Ribavirin, the only clinically approved drug known to target eIF4E, is an anti-viral molecule currently used in hepatitis C therapy. The potential of ribavirin to treat CRC remains largely unknown. Ribavirin treatment in CRC cell lines drastically inhibited cell proliferation and colony formation, induced S phase arrest and reduced cyclin D1, cyclin A/E and proliferating cell nuclear antigen (PCNA) levels in vitro, and suppressed tumorigenesis in mouse model of colitis-associated CRC. Mechanistically, ribavirin treatment significantly reduced PRMT5 and eIF4E protein levels and the accumulation of symmetric dimethylation of histone 3 at arginine 8 (H3R8me2s) and that of histone 4 at arginine 3 (H4R3me2s). Importantly, inhibition of PRMT5 by ribavirin resulted in promoted H3R8 methylation in eIF4E promoter region. Our results demonstrate the anti-cancer efficacy of ribavirin in CRC and suggest that the anti-cancer efficacy of ribavirin may be mediated by downregulating PRMT5 levels but not its enzymatic activity.

The Antimalarial Drug Pyronaridine Inhibits Topoisomerase II in Breast Cancer Cells and Hinders Tumor Progression In Vivo

BACKGROUND

Breast cancer is the most frequently diagnosed cancer in women worldwide. Pyronaridine (PND), an antimalarial drug, was shown to exert anticancer activity on seventeen different human cancer cells, seven from female breast tissue. Additionally, PND induced apoptosis via mitochondrial depolarization, alteration of cell cycle progression, and DNA intercalation. However, the molecular target of PND in cells was not elucidated.

OBJECTIVE

Here, we have further investigated PND's mode of action by using transcriptome analysis. Preclinical studies were also performed to determine whether PND could affect tumor progression in a human breast cancer xenograft in mice. Moreover, we assessed the combined efficacy of PND with well-known anticancer drugs.

METHODS

Transcriptome analyses of PND-treated cancer cells were performed. Topoisomerase II activity was evaluated by an in vitro assay. In addition, daily oral administration of PND was given to mice with human breast cancer xenografts. The differential nuclear staining assay measured in-vitro cell toxicity.

RESULTS

The transcriptome signatures suggested that PND might act as a topoisomerase II inhibitor. Thus, topoisomerase inhibition assays were performed, providing evidence that PND is a bona fide topoisomerase II inhibitor. Also, in-vivo studies suggest that PND hinders tumor progression. Besides, combination studies of PND with anticancer drugs cisplatin and gemcitabine revealed higher cytotoxicity against cancer cells than individual drug administration.

CONCLUSION

The findings provide evidence that PND is a topoisomerase II inhibitor and can hinder cancer progression in an animal model, further demonstrating PND's favorable characteristics as a repurposed anticancer drug.

Patient-derived xenografts and organoids model therapy response in prostate cancer

Therapy resistance and metastatic processes in prostate cancer (PCa) remain undefined, due to lack of experimental models that mimic different disease stages. We describe an androgen-dependent PCa patient-derived xenograft (PDX) model from treatment-naïve, soft tissue metastasis (PNPCa). RNA and whole-exome sequencing of the PDX tissue and organoids confirmed transcriptomic and genomic similarity to primary tumor. PNPCa harbors BRCA2 and CHD1 somatic mutations, shows an SPOP/FOXA1-like transcriptomic signature and microsatellite instability, which occurs in 3% of advanced PCa and has never been modeled in vivo. Comparison of the treatment-naïve PNPCa with additional metastatic PDXs (BM18, LAPC9), in a medium-throughput organoid screen of FDA-approved compounds, revealed differential drug sensitivities. Multikinase inhibitors (ponatinib, sunitinib, sorafenib) were broadly effective on all PDX- and patient-derived organoids from advanced cases with acquired resistance to standard-of-care compounds. This proof-of-principle study may provide a preclinical tool to screen drug responses to standard-of-care and newly identified, repurposed compounds.

Drug Repurposing: An Emerging Tool for Drug Reuse, Recycling and Discovery

Drug repositioning or repurposing is a revolutionary breakthrough in drug development that focuses on rediscovering new uses for old therapeutic agents. Drug repositioning can be defined more precisely as the process of exploring new indications for an already approved drug while drug repurposing includes overall re-development approaches grounded in the identical chemical structure of the active drug moiety as in the original product. The repositioning approach accelerates the drug development process, curtails the cost and risk inherent to drug development. The strategy focuses on the polypharmacology of drugs to unlocks novel opportunities for logically designing more efficient therapeutic agents for unmet medical disorders. Drug repositioning also expresses certain regulatory challenges that hamper its further utilization. The review outlines the eminent role of drug repositioning in new drug discovery, methods to predict the molecular targets of a drug molecule, advantages that the strategy offers to the pharmaceutical industries, explaining how the industrial collaborations with academics can assist in the discovering more repositioning opportunities. The focus of the review is to highlight the latest applications of drug repositioning in various disorders. The review also includes a comparison of old and new therapeutic uses of repurposed drugs, assessing their novel mechanisms of action and pharmacological effects in the management of various disorders. Various restrictions and challenges that repurposed drugs come across during their development and regulatory phases are also highlighted.

Pathway-Based Drug-Repurposing Schemes in Cancer: The Role of Translational Bioinformatics

Cancer is a set of complex pathologies that has been recognized as a major public health problem worldwide for decades. A myriad of therapeutic strategies is indeed available. However, the wide variability in tumor physiology, response to therapy, added to multi-drug resistance poses enormous challenges in clinical oncology. The last years have witnessed a fast-paced development of novel experimental and translational approaches to therapeutics, that supplemented with computational and theoretical advances are opening promising avenues to cope with cancer defiances. At the core of these advances, there is a strong conceptual shift from gene-centric emphasis on driver mutations in specific oncogenes and tumor suppressors-let us call that the silver bullet approach to cancer therapeutics-to a systemic, semi-mechanistic approach based on pathway perturbations and global molecular and physiological regulatory patterns-we will call this the shrapnel approach. The silver bullet approach is still the best one to follow when clonal mutations in driver genes are present in the patient, and when there are targeted therapies to tackle those. Unfortunately, due to the heterogeneous nature of tumors this is not the common case. The wide molecular variability in the mutational level often is reduced to a much smaller set of pathway-based dysfunctions as evidenced by the well-known hallmarks of cancer. In such cases "shrapnel gunshots" may become more effective than "silver bullets". Here, we will briefly present both approaches and will abound on the discussion on the state of the art of pathway-based therapeutic designs from a translational bioinformatics and computational oncology perspective. Further development of these approaches depends on building collaborative, multidisciplinary teams to resort to the expertise of clinical oncologists, oncological surgeons, and molecular oncologists, but also of cancer cell biologists and pharmacologists, as well as bioinformaticians, computational biologists and data scientists. These teams will be capable of engaging on a cycle of analyzing high-throughput experiments, mining databases, researching on clinical data, validating the findings, and improving clinical outcomes for the benefits of the oncological patients.

Drug rechanneling: A novel paradigm for cancer treatment

Cancer continues to be one of the leading contributors towards global disease burden. According to NIH, cancer incidence rate per year will increase to 23.6 million by 2030. Even though cancer continues to be a major proportion of the disease burden worldwide, it has the lowest clinical trial success rate amongst other diseases. Hence, there is an unmet need for novel, affordable and effective anti-neoplastic medications. As a result, a growing interest has sparkled amongst researchers towards drug repurposing. Drug repurposing follows the principle of polypharmacology, which states, "any drug with multiple targets or off targets can present several modes of action". Drug repurposing also known as drug rechanneling, or drug repositioning is an economic and reliable approach that identifies new disease treatment of already approved drugs. Repurposing guarantees expedited access of drugs to the patients as these drugs are already FDA approved and their safety and toxicity profile is completely established. Epidemiological studies have identified the decreased occurrence of oncological or non-oncological conditions in patients undergoing treatment with FDA approved drugs. Data from multiple experimental studies and clinical observations have depicted that several non-neoplastic drugs have potential anticancer activity. In this review, we have summarized the potential anti-cancer effects of anti-psychotic, anti-malarial, anti-viral and anti-emetic drugs with a brief overview on their mechanism and pathways in different cancer types. This review highlights promising evidences for the repurposing of drugs in oncology.

Drug combination and repurposing for cancer therapy: the example of breast cancer

Cancer is a set of extremely complex diseases, which are increasingly prominent today, as it affects and kills millions of people worldwide, being the subject of intense study both in its pathophysiology and therapy. Especially in women, breast cancer is still a cancer with a high incidence and mortality. Even though mortality rates for this type of cancer have declined in recent years, it remains challenging at the treatment level, especially the metastatic type. Due to all the impact on health, cancer therapy is the subject of costly and intense research. To enrich this therapy, as well as decrease its underlying high associated costs, drug repurposing and drug combinations are strategies that have been increasingly studied and addressed. As the name implies, drug repurposing presupposes giving new purposes to agents which, in this case, are approved for the therapy of other diseases (for example, cardiovascular or metabolic diseases), but are not approved for cancer therapy. Therefore, a better knowledge of these therapeutic modalities for breast cancer therapy is crucial for improved therapy. In this particular review, we will discuss some relevant aspects of cancer and, particularly, breast cancer and its therapy. Also, drug combination and repurposing will be highlighted, together with relevant examples. Despite some limitations that need to be overcome, these methodologies are extremely important and advantageous in combating several current problems of cancer therapy, namely in terms of costs and resistance to current therapeutic modalities. These approaches will be explored with a special focus on breast cancer.

Drug repurposing using transcriptome sequencing and virtual drug screening in a patient with glioblastoma

Background Precision medicine and drug repurposing are attractive strategies, especially for tumors with worse prognosis. Glioblastoma is a highly malignant brain tumor with limited treatment options and short survival times. We identified novel BRAF (47-438del) and PIK3R1 (G376R) mutations in a glioblastoma patient by RNA-sequencing. Methods The protein expression of BRAF and PIK3R1 as well as the lack of EGFR expression as analyzed by immunohistochemistry corroborated RNA-sequencing data. The expression of additional markers (AKT, SRC, mTOR, NF-κB, Ki-67) emphasized the aggressiveness of the tumor. Then, we screened a chemical library of > 1500 FDA-approved drugs and > 25,000 novel compounds in the ZINC database to find established drugs targeting BRAF47-438del and PIK3R1-G376R mutated proteins. Results Several compounds (including anthracyclines) bound with higher affinities than the control drugs (sorafenib and vemurafenib for BRAF and PI-103 and LY-294,002 for PIK3R1). Subsequent cytotoxicity analyses showed that anthracyclines might be suitable drug candidates. Aclarubicin revealed higher cytotoxicity than both sorafenib and vemurafenib, whereas idarubicin and daunorubicin revealed higher cytotoxicity than LY-294,002. Liposomal formulations of anthracyclines may be suitable to cross the blood brain barrier. Conclusions In conclusion, we identified novel small molecules via a drug repurposing approach that could be effectively used for personalized glioblastoma therapy especially for patients carrying BRAF47-438del and PIK3R1-G376R mutations.

Repurposing Anti-Cancer Drugs for COVID-19 Treatment

The novel coronavirus disease 2019 (COVID-19) pandemic has caused catastrophic damage to human life across the globe along with social and financial hardships. According to the Johns Hopkins University Coronavirus Resource Center, more than 41.3 million people worldwide have been infected, and more than 1,133,000 people have died as of October 22, 2020. At present, there is no available vaccine and a scarcity of efficacious therapies. However, there is tremendous ongoing effort towards identifying effective drugs and developing novel vaccines. Early data from Adaptive COVID-19 Treatment Trials (ACTT) sponsored by the National Institute of Allergy and Infectious Diseases (NIAID) and compassionate use study have shown promise for remdesivir, leading to emergency authorization by the Food and Drug Administration (FDA) for treatment of hospitalized COVID-19 patients. However, several randomized studies have now shown no benefit or increased adverse events associated with remdesivir treatment. Drug development is a time-intensive process and requires extensive safety and efficacy evaluations. In contrast, drug repurposing is a time-saving and cost-effective drug discovery strategy geared towards using existing drugs instead of de novo drug discovery. Treatments for cancer and COVID-19 often have similar goals of controlling inflammation, inhibiting cell division, and modulating the host microenvironment to control the disease. In this review, we focus on anti-cancer drugs that can potentially be repurposed for COVID-19 and are currently being tested in clinical trials.

Recycling the Purpose of Old Drugs to Treat Ovarian Cancer

The main challenge in ovarian cancer treatment is the management of recurrences. Facing this scenario, therapy selection is based on multiple factors to define the best treatment sequence. Target therapies, such as bevacizumab and polymerase (PARP) inhibitors, improved patient survival. However, despite their achievements, ovarian cancer survival remains poor; these therapeutic options are highly costly and can be associated with potential side effects. Recently, it has been shown that the combination of repurposed, conventional, chemotherapeutic drugs could be an alternative, presenting good patient outcomes with few side effects and low costs for healthcare institutions. The main aim of this review is to strengthen the importance of repurposed drugs as therapeutic alternatives, and to propose an in vitro model to assess the therapeutic value. Herein, we compiled the current knowledge on the most promising non-oncological drugs for ovarian cancer treatment, focusing on statins, metformin, bisphosphonates, ivermectin, itraconazole, and ritonavir. We discuss the primary drug use, anticancer mechanisms, and applicability in ovarian cancer. Finally, we propose the use of these therapies to perform drug efficacy tests in ovarian cancer ex vivo cultures. This personalized testing approach could be crucial to validate the existing evidences supporting the use of repurposed drugs for ovarian cancer treatment.